I use water to clean my pipes. At my place in Brazil, I only have room-temperature water. Can't be bothered to boil/heat some, and I don't use a hot water system here to heat tap water because it's not really needed. It still works fine with room temperature water.
When not here, I use hot tap water, and it seems to work fine too.
I also went so far as to load up my pipes with soap suds and went to work with a shank brush to get them very clean. It is a *neutral* soap without moisturizers, scents, etc.
But... last week, I was twisting the stem off of one of my pipes and the shank came off with it. It was a Tsuge with a fat knuckle of bamboo. Maybe the water caused this. Maybe the relative humidity of where I'm at in Brazil caused it. Hard to say. Beware, I guess. I applied some crazy glue to an area that I figured would not be exposed to the inner chamber and put it back on. Seems tight now.
Side note: That pipe was clean when the shank came off. But, there seemed to be a gap in the bamboo/briar shank connection that was impossible to clean. Without the bamboo shank, I was able to scrape a fair amount of built up gunk where the bamboo met the briar portion of the shank. It was a bit disappointing, because I couldn't see how to clean that part of the pipe without the bamboo there. And obviously, you normally can't take the bamboo off to clean it. Poor construction I was not meant to see, I guess.
Further side note: I have a Dunhill bamboo shank pipe and the mouth piece, where it fits into the bamboo shank, came off once. There is a small piece of plastic that inserts into the bamboo, so that the mouth piece/stem can fit in. One day, the inner plastic piece twisted out. This was before I was washing with water and that pipe lives in Canada. It's on the west coast, which I guess is also humid, but my home there is not humid, so I'm not sure what caused it.
Could just be an issue of bamboo shanks, I don't know.
As to every other pipe I have, the water seems to work just fine. Haven't noticed any ill effects and they taste great. They dry very fast too. I know it's heresy, but I also love the effect of soap and a shank brush for the shank and the bowl. I get a load of suds and just brush the hell out of it. My pipes taste great after that treatment, but to be very clear, I only use unscented, non-moisturized, basic soap. It's very easy to find in Brazil. I'm sure I'll find a solution in Canada as well, despite much of the soap offerings being adulterated with scents, moisturizers, etc. They must have a brand for sensitive skin or something.
A lot of people will jump out of their seats, but water and suds... Now that is clean. Try it out on a beater pipe to see how it goes.